The present disclosure relates to a process and apparatus for the production of a H2-containing product and a CO-containing product with a CO-containing product turndown capability.
H2 and CO can be produced from a common crude synthesis gas production unit using a first process train for producing the H2 and a second process train for producing CO. The H2 can be produced by passing a first portion of the crude synthesis gas to a shift reactor and passing the shifted and dewatered synthesis gas to a pressure swing adsorption unit. The CO can be produced by passing a second portion of crude synthesis gas to a CO2 removal unit and passing the CO2-depleted synthesis gas to a cryogenic separation unit.
Each of the process trains are designed for a specific production rate of their respective products.
When the requirement from the customer or downstream process for the CO is reduced or stopped (short or intermediate term), the flow rate of the crude synthesis gas to the second process train is reduced and the cryogenic separation unit is turned down. The problem is that the turn down for cryogenic separation units is limited, for example to 30% to 45% of their design capacity. When the requirement from the customer or downstream process for the CO is reduced below the turndown capability of the cryogenic separation unit, the unneeded CO is used as a fuel or flared.
Shutting down the CO producing train is problematic due to the long time required to start up the cryogenic separation unit and the CO2 removal unit.
Shutting down the CO producing train may also be problematic due to effects on heat transfer equipment that is integrated between H2-production train and the CO-production train.
Industry desires to be able to turn down CO production without having to flare the CO and/or minimizing the amount of CO used as fuel.
Industry desires to improve overall production efficiency during production turndown modes.